Chemical analysis of nickel-titanium rotary instruments with and without electropolishing after cleaning procedures with sodium hypochlorite.
The aim of this study was to chemically analyze rotary nickel-titanium instruments with and without electropolishing after cleaning procedures with NaOCl. To evaluate the effect of 5.25% NaOCl on electropolished RaCe instruments, a total of 18 instruments were tested. A control group of 18 nonelectropolished RaCe instruments was used. The surface of each instrument was analyzed before and after cleaning in NaOCl by using energy dispersive x-ray analysis, Auger electron spectroscopy, and scanning electron microscopy. Surface defects were recorded, and a chi(2) test was used for statistical analysis. After immersion in NaOCl, the nonelectropolished and electropolished files showed a significant increase of iron deposits as a result of galvanic corrosion of the shaft (P < .05). The nonelectropolished files showed marked presence of NaCl deposits in the machining marks and microcracks. As regards the chemical nature of the surface, the electropolished files had an oxide increase compared with the low oxide concentration (mainly TiO2) before cleaning. The nonelectropolished files already possessed higher oxides concentration (TiO2 and NiO) before NaOCl cleaning. NaOCl treatment affects the chemical composition of the surface and, in particular for nonelectropolished instruments, of the bulk exposed through machining marks and fabrication microcracks.
Bonaccorso
Antonio
A
Private practice, Catania, Italy. Electronic address: endomaterials@fastwebnet.it.
Schäfer
Edgar
E
Department of Operative Dentistry, University of Münster, Münster, Germany.
Condorelli
Guglielmo Guido
GG
Department of Chemical Science, University of Catania, Catania, Sicily, Italy.
Cantatore
Giuseppe
G
Faculty of Dentistry, University of Verona, Verona, Italy.
Tripi
Teresa Roberta
TR
Faculty of Dentistry, University of Catania, Catania, Sicily, Italy.
D003343:Corrosion; D003666:Decontamination; D003722:Dental Alloys / Q000737:chemistry; D019551:Dental Disinfectants / Q000737:chemistry*; D003762:Dental Instruments; D003775:Dental Polishing; D055664:Electrochemical Techniques; D004577:Electron Probe Microanalysis; D008855:Microscopy, Electron, Scanning; D009532:Nickel / Q000737:chemistry; D010087:Oxides / Q000032:analysis; D011897:Random Allocation; D018915:Root Canal Preparation / Q000295:instrumentation*; D012965:Sodium Chloride / Q000032:analysis; D012973:Sodium Hypochlorite / Q000737:chemistry*; D013057:Spectrum Analysis / Q000379:methods; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry
D003722:Dental Alloys; D019551:Dental Disinfectants; D010087:Oxides; C040654:titanium nickelide; D012965:Sodium Chloride; D009532:Nickel; D014025:Titanium; D012973:Sodium Hypochlorite